There is something oddly weird about this show. Think of it like Dragon maid. While there are for sure, sus moments, and moments that are very questionable. Because underneath some questionable material, is something that is actually quite wholesome, and really knowledgeable for that matter. But also, something I doubt many will touch upon, that it's not too perverted? Like, one would suspect that it would completely dive in that direction from the MC, going from a boy to a girl, but weirdly enough, it's more tame in that department.There are still moments that hit that way, but they're not major as one would think. Which is quite nice, as if we had a pervy MC, it'd be a bit more disturbing.
Story and characters:7
To go over the show, as it's explained in the synopsis. Sister turns her big brother into a little sister, and how now she is adapting to the change, but how the sister is monitoring and studying him. but with a sweet side to it. As if she really wants to help her sibling live a happy life, to be happy with where they are, rather than being a shut in with no friends. Because honestly, despite their differences in ability and popularity level. They have quite an honest and good sibling love for one another. There is a legit care between them, and that is the major wholesomeness to this. It's a weird watch yes, but wholesome? Can't deny that it isn't.
I've touched on a bit on the characters, but to go in further, I would say there are a lot I can see from Dragon maid, by that I mean in terms of an upbeat tone of content, and driven character. The sister seems like a perfect person who can do anything, but is a big sweetheart, despite a few weird sides to her, but she's having fun having a little sister, whom is the onichan she cares for. As for Mahiro themselves, throughout the show, I expect them to change over time, but they're good too. The sister may be the stand out. But the loner is the one who was the excellent older sibling, that made the strong relationship possible. They're a great character.
Art and sound: 8
Honestly, the animation reminds of like Do it yourself from the previous season. A colourish, but looking more cartoonish look in parts. It's a style that works, and works well with the animes contents, and doesn't look bad at all. While some go for a more breathtaking experience, this uses a good simple palette, and does it well. With a great matching scene by scene sound design, to really run the anime home.
Oniichan may certainly be weird, like really. But there is an honest to good, wholesome vibe about it, that makes it a must watch for sure. Long as it doesn't go too weird that is. But from the first three episodes, it's certainly been a wholesome experience for sure.